Rated



Patented Nov. e6, 1928. V

UNITED TATE-S11 l JOHNF. 'rooMEY, or new vonx, Y Ann ,enoRGE n. DUHNKRACK, or JERSEY our, NEW messy, assrcnoas'ro BELL TELEPHONE =LABGRATORIES,-INCORLEO-v RATED, on NEW YORK, N; AooRroRArIoN oF'NEw oRKj v TELEPHONE SYsTEMQ Application filed December 28, 1927; Serial No. 243,059.

This inventionrelates to telephone sy's-' terns and-particularly to circuitv arrangements associated with long distance trans- V relays associated therewith were restored.

mission lines ata central ofiice.

In general practice a long distance trans? mission line may be associatedwlth a plurality of-difi'erent switchboards and posi-V tions at a central office. It may'be found desirableysuch as at night, when a. decrease "in traflic mayWa-rrant a decrease in-the operating force at a central office, 'to have both incoming and outgoing calls over the long distancelines handled at positions on a board which would normally be used for only one type of call; In instances when a call is received at an incoming board which requires theattention of a through operator, such as an operator at an outgoing board, itis desirable to transfer such a call to an outgoing board; g

Heretofore such systems have been devised and satisfied the requirements imposed by traffic conditions, butthe volume of toll traffic'has increased to such an extent as to necessitate a toll boards of increased size which results in correspondingly increased demands upon the switchboard:circu'its,

It is the object of this invention to improve the equipment located at toll switch boards in such a manner as to satisfy the increased demands made upon toll line equipment. Q

This object is attained in'accordance with a feature ofthe invention by the provision of a toll line circuitiprovided with transfer equipment which permits the transfer of calls between boards in a central oflice.

Anotherlfeature of the invention resides in a circuit arrangement'whereby a call at one board may not be transferred to another boa-rd at which no signals to indicate the transfer are available. This feature'is particularly applicable to large toll oflices wherein it is found desirable to provide only a certain percentage of toll linesavailable at that otfice, with transfer facilities. For

* the sake'of uniformity in construction and assembly, each board i provided with a certain number of 'transferke'ys, which num ber'usually does not correspond to-the number of lines that have transfer facilities,'so that the accidental actuation of a key corresponding to such a line would ordinarily cause the transfer of a call without the other; equipment."

form; j 1

transmission of a signal and would render the call lost and the particular toll line in accessible to further calls until the transfer The-present feature does not permit the transfer circuit to function unless thereisan operative signal associated therewith,

) Generally stated, the invention f-contenr plates the use of a transfer circuitwv'her'ein the relay which effects the signal transferfirst operates in'series with the signal to be actuated and upon operating, locks up independent of the signal and causes the signal tobe actuated in a circuit freeof all The invention may now be more; fully understood from the following detailed description made with referenceto theaccom- Epanying drawing which illustrates a circuit diagram of the invention in" its preferred Y The toll line L is shown terminating in an exchange at a plurality of positions, -A, B, C and D. The positions A a nd D indicate respectively the service observingposition and the inward position, whereas Band C represent through positions located at different switchboards. It will now be assumed that the toll line L has been seized at a distant'oflicein the establishmentof a connection and that signaling current has been appliedtothe line .in any well-known manner. Relay 10 being normally bridged across the tip and ring conductors'of the line circuit L, responds to the signaling current incoming over the line and in attracting its-armaturecau'ses relay 11 to operate ina circuit; extending from grounded battery, outer left-hand armature and back contact of relay" 12, winding of relay 11, front contact lay 10 to ground.

Relay l1 uponoperating causes relay 13 to operate byway of its right-hand winding. Relay 1S infattracting its outermost and armature of rearmaturecauses the drops 14:, 15, 16. and "17 and all multiply drops associated with the line; L, to be 'actuated over an obvious cirnoting the illunr contact of relay 12, middle armature and front contact of relay 13, frontcontact and innermost armature of relay 18, inner left. hand armature and back contact of relay 18, through the filaments of lamps 19 and at the service observing position A and the inward position D respectively to ground.

Lamps 19 and 22 are lighted in "this-circuit and indicate to the operators located at the positions at which these lamps are situated that a call. is awaiting attention on th toll line L. Agcording to general practice the operator at the inward position-D upon tion of lamp 22 answers the call by inserting plug 23 of the answering end of the cord circuit E into jack 2-iassociated with the lighted line lamp 22. The operator at the service observing posi tion may plug into the connection by way of the jack 35 at position A in order to observe the progress of the call.

Upon the insertion of plug 23 into gack Qi: relay 12 operates in a circuit extending from grounded battery, resistance element 88, sleeve contacts of plug 28,oand jack 24:, back contact and outer left-hand armature of relay 18 to ground through the winding of relay 12. Relay 12 attracting its righthand armature, removes the ringing relay from across the tip and ring conductors of the line circuit L, thereby improving transmission. In attracting its outer lefthand armature relay 12 opens the locking circuit for relay 13, which relay thereupon releases, extinguishing the line lamps 19 and at positionsA and B. At its inner lefthand armature and front contact relay 12 supplies battery to the busy signals 1 1, 15, 16 and 17 to maintain them actuated after the release of relay 13.

Should the nature of the incoming call be such as to require the attention of a through operator, the operatorat the inward position D proceeds to transfer the callv to a through operator by momentarily actuating the transfer key 25.

Relays 13 and 18 now operate in a circuit extending fromgrounded battery, right hand winding of relay 13, left-hand winding of relay '18, to ground by way of the alternate contacts of. key 25. In attracting its outer lefthand armature relay 18 opens the circuit for relay 12, whereupon the operation of relay 13 performs the same functions as hereinbefore described in connection with its initial operation with g the exception of the lighting of lamp 19. At its inner lefthand armature relay 18 opensthe circuit to the lamps 19 and 22, and also closes a circuit for relay 26 extending from grounded battery, outer left-hand armature and back cont ct of relay 12 winding of relay 26. back contact and left-hand armature of relay 26. right-hand armature and front contact of relay 18, to ground through the filament of lamp 20stthe through position B. Lamp 20 at position and similar lamps at other through position do not light in this circuit owing to theinclusion of the windingof relay therein. However, relay 26' 013- crates and in'a ttracting its lefthand armature causes the lamps such" as 20 at the throughfpositions to be lighted in a circuit eiclusi've of any relay winding such as that of 2G. 7 Relay 26 now locks in series with the right-hand winding of relay 18. This looking circuit may be traced from grounded battery, outer left hand armature and back contact of relay 12, winding oflrelay 26, closed contacts of relay right-hand winding of relay 18 to. ground. At itsrigl1tl1and armature, relay 26 causes lamp 21 at the throughposltlon C to be lighted. An

)roceed to handle the callb insertin the l y a plug of am answering cord into a jack such as 28 or 29, whereupon relay S0 is caused to operateover thesleeve circuit; Relay 30 at its two outer. armatures, disassociates the jack 2 1 at the inward position D, and all other corresponding jacks from the line circuit, removing all surplus cable from the connection and preventing disturbances caused by operators plugging into these multiplejacks, thereby afiiordingbetter trans mission on through connections. At its inner upper armaturerelay 30 connects battery to the winding of relay 12 through resistance 31 to cause this relay to operate and perform the same functions hereinbet'ore described in connection with its operation when the incoming call was answered by the operator at the inward position D. v p i i From the foregoing description of the transfer operation it is evident that there is no possibility of losing a call upon the accidental actuation of a transfer key on a line which is not provided with signal lamps at the through positions. since neither relay 18 nor 26 can lock up if the lam s such as of sets of switching terminals, a signal at each of said sets of terminals, means responsive to a call incoming on said transmission line for operating one of said signals, a relay. and means for effecting the operation of said relay in series with another of said '0 )erator at an of the through )ositions ma signals and thereafter maintaining said relay and said second signal operated in separate circuits. v

2. In a telephone exchange system, a transmission line terminating in a plurality of' sets of switchingterminals, a signal at each of said sets of terminals, means responsive to a call incoming on said transmission line for operating one of said signals, a relay,

and manually controlled means for effecting a signal at another position for said first mentioned signal, the operation of said relay depending upon the receptive condition of the signal at said second mentioned position.

4;. In a telephone system, a line terminating at a plurality of positions, a signal at each of said positions, means responsive to a call incoming over said line for actuating the signal at one of said positions, a transfer relay, -a key, and means controlled by said key for connecting said transfer relay in a series circuit with a signal at another position, said relay, upon operating, adapted each of said positions, means responsive to operate said second signal in a circuit independent of said relay.

5. In a telephone system, a line terminating at a plurality of positions, a signal at to a call incoming over said line for actuating the signal at one of said positions, a transfer relay, a key, and means controlled by said key for connecting said transfer relay in a series circuit with a signal at another position, said relay, upon operating, adapted to lock in a circuit independent of said second signal.

opera-ted.

6. In a telephone system, a line terminating at a plurality of positions, a signal at each of said positions, means responsive to a call incoming over said line for actuating 'the signal at one of said positions, a transfer relay, a key, andmeans controlled by said key for connecting said transfer relay in a series circuit with a signal at anotherposi tion, said relay,gupon operating, adapted to 'lockin a circuit independent of said second signal and maintain said second signal 7. In a telephone system, a line circuit terminating at a plurality of positions, a signal at each of said positions, means responsive to a call incoming over said line foractuating one of said signals, a relay,

a second relay, manually operated means for actuating said first relay to disable said sig- 1 Hal and connect another of said signals in series with said second relay whereupon said second'relay operates and disassociates its winding from the circuit of said second[ signal. v I r v 8. In a signal transfer circuit, a signal, a relay, a second relay, and means for actuating said first relay to cause said signal and said second relay to be connected in a series circuit and said second relay to be operated whereupon said second relay locks in a circuit independent of said signal.

9.'In a signal transfer circuit, a signal,

a relay, a: second relay, and means for actuatingsaid first relay to cause said signal and said second relay to be connected in a serles circuit and said second relay to be operated I whereupon said second relay locks in series with said first relay in a circuit independent of said signal.

' In witness whereof, we hereunto subscribe our names this 27th day of December, A. D. 1927. v 1

, JOHN ETOOMEY. I GEORGE DUHNKRACK. 

